Hand-piece of dentistry with an air-driven turbine

ABSTRACT

The air-driven rotor of the turbine is journaled at its two ends in air bearings comprising floating sleeves. These sleeves are supported within the cylindrical wall of a housing of the handpiece by means of inflated plastic shells, each composed of two annular parts having a V-shaped cross section. Air under pressure is supplied simultaneously for inflating the shells and to the air bearings by derivative conduits of the main conduit supplying the turbine with the driving air jet.

United States Patent 72) Inventor David Mosimann Clos du Lac 3, Bienne(canton of Berne), Switzerland [21 Appl. No. 837,463 [22] Filed June 30,1969 [45] Patented June 29, 1971 [32] Priority July 1, 1968 [33]Switzerland [31] 9777/68 [54] HAND-PIECE 0F DENTISTRY WITH AN AIR-DRIVEN TURBINE 3 Claims, 2 Drawing Figs.

[52] U.S.Cl 415/112, 415/503, 308/9 [51] lnt.Cl ..F0ld 11/00, F03b 13/04{50] FieldoiSearch 415/112, 119, 503; 308/9, 26; 277/59, 205; 32/27,DIG. l

[56] References Cited UNITED STATES PATENTS 3,088,707 5/1963 Williams eta1. 31/27 Primary Examiner-Henry F. Raduazo Attorney-Stevens, Davis,Miller 8: Mosher ABSTRACT: The air-driven rotor of the turbine isjoumaled at its two ends in air bearings comprising floating sleeves.These sleeves are supported within the cylindrical wall of a housing ofthe hand-piece by means of inflated plastic shells, each composed of twoannular parts having a V-shaped cross section. Air under pressure issupplied simultaneously for inflating the shells and to the air bearingsby derivative conduits of the main conduit supplying the turbine withthe driving air jet.

PATENTED JUNZS I97! HAND-PIECE F DENTISTRY WITH AN AIR-DRIVEN TURBINEBACKGROUND OF THE INVENTION 1. Field of the Invention 1 This inventionrelates to air-driven dental turbines for handpieces and in particularto dental turbines having, on 'either side of the bucket-wheel of therotor, an air bearing comprising a floating sleeve for the distributionof air under pressure to the bearing, said floating sleeve being held ina housing by means of a pair of yielding gaskets located between thesleeve and the sidewall of the housing, on either side of a centralairsupply conduit.

2. Description of the Prior Art With the known turbines of this typeeach floating sleeve is supported by two gaskets having a circular crosssection: In order that these gaskets operate in the desired manner,namely so as to permit the two floating sleeves serving as bearings forthe turbine rotor of automatically aligning themselves relative to eachother and the noise produced by the turbine rotor of being substantiallymuffled, the gaskets have to be made out of a very soft material.

However, the last condition has several drawbacks. First of all,manufacturing gaskets out of such a material with precise sizes isrelatively difficult. Moreover, gaskets made out of a soft material donot well withstand subjection to a relatively high temperature so thatthe turbine cannot be sterilized by heating to the required extent.Since the gaskets of the known turbines are furthermore subjected to apressure when the sleeves supported by them move in a transversedirection, the surfaces between which the gaskets are located have to bemanufactured with a very great precision or else the gaskets would holdthe corresponding sleeves in such positions that these sleeves would notbe aligned with respect to each other. Finally, these gaskets obviouslydo not permit the stiffness of the suspension of the sleeves serving asbearings for the turbine rotor to be modified.

SUMMARY OF THE INVENTION The main object of this invention is to providea turbine of the type indicated above while avoiding the above-mentioneddrawbacks. I

With the turbine improved according to the invention the floatingsleeves of the air bearings of the turbine rotor are supported withinthe housing of the hand-piece by means of inflated plastic shells. Eachshell is advantageously composed of 7 two annular parts, each having aV-shaped cross section. Each shell part is, moreover, set in such aposition that one of its flanges bears on the floating sleeve while theother flange bears against the sidewall of the hand-piece housing, thefree spaces comprised between the flanges of the two shell parts holdingeach of said sleeves thereby being directed toward each other.

Further objects of the invention will become apparent in the course ofthe following description.

BRIEF DESCRIPTION OF THE DRAWING One embodiment of the turbine improvedaccording to the invention is represented diagrammatically and by way ofexample in the accompanying drawings.

In the drawings:

FIG. I is an axial section of the turbine and FIG. 2 is a partialcross-sectional view on a larger scale of a part of the turbinerepresented in FIG. 1.'

DESCRIPTION OF THE PREFERRED EMBODIMENT In the embodiment represented inthe drawings the turbine is mounted in the contra-angle (only the head 1of which has been represented in FIG. 1) which is secured to the handleof the hand-piece for receiving the different rotatory tools used by thedentists. The turbine rotor firstly comprises a spindle 2 carrying achuck 3 arranged for gripping the different tools usually employedwith'this type of instrument (milling-cutters, grinding tools, etc.). Abucket-wheel 4 of usual shape is set on spindle 2 as well as two sleeves5 and 6 carrying the bearing surfaces by means of which the turbinerotor is journaled within the contra-angle of the hand-piece. The threemembers 4, 5 and 6 are set on spindle 2 in such a manner as to form asingle unit therewith. A stationary sleeve 7, 8 surrounds each rotatorysleeve 5, 6. Each stationary sleeve 7, 8 comprises two cylindricalpieces 9, 10 set with force fit into one another. Pairs of bores 11 areprovided through piece 9 at places regularly staggered around the axisthereof. The corresponding bores 11 of each one of these pairs open intwo annular grooves 12 provided in the outer surface of piece 9. Axialgrooves 13 provided in the same surface of piece 9 provide for acommunication between the two annular grooves 12. The outer piece 10 ofeach sleeve 7, 8 is provided with an annular groove 14 in its innersurface, which communicates with the axial grooves 13 of piece 9. Groove14, in turn, communicates with the outer surface of piece 10 by somebores 15 provided through the wall of piece 10. Two grooves 16 arefinally provided in such a manner in the outer surface of sleeve 10 thatan annular rim 17 remains therebetween. Bores 15 open in the outersurface of rim 17 and grooves 16 leave flanges 18 near the ends ofpiecelt). Each sleeve 7, 8 thus includes a manifold having inletopenings 15 and outlet openings 11 for distributing the air of the airbearings.

The turbine rotor as well as sleeves 7 and 8 are located in a housing ofhead 1 having a substantially cylindrical sidewall. Head 1 thus servesas a support for the turbine rotor and its air bearings which areaxially held in place in head 1 by a cover member 19 set with force fitin head 1 to which it is definitely secured.

FIG. 1 shows that the sleeves 7 and 8 have a free play in an axial aswell as in a transverse direction between the turbine rotor and head 1.Sleeves 7 and 8 are accordingly floating and are thus able to take theconvenient position between the turbine rotor and its housing. A shellpart 20 is inserted in each of the two grooves 16 of sleeves 7 and 8.

In the rest position, which is represented in FIG. 2, each shell part 20has a V- shaped cross section and thus comprises a an inner flange 21and an outer flange 22. When parts 20 are set in place, their flanges 21and 22 firmly bear against the bottom of grooves 16 and the sidewall ofthe rotor housing formed in head 1 and including cover member 19. Asshown in FIG. I, shell parts 20 are oriented in such a manner in theircorresponding grooves that the free spaces 23 enclosed between theflanges 21, 22 of the two shell parts 20 mounted on the same floatingsleeve are directed toward each other. FIG. 1, moreover, shows that thesizes of shell parts 20 are chosen with respect to those of grooves 16so that their outer flanges 22 leave a free annular space 24 betweenthem, space 24 surrounding rim 17.

The bucket-wheel 4 and the air bearings of the turbine rotor aresupplied with air under pressure through the handle of the hand-piecewhich is provided therefore with a central main conduit 25 as well aswith two derivative conduits 26. While the air passing through conduit25 actuates the bucket-wheel 4, that which passes through the conduit 26is distributed to the air bearings of the turbine rotor through themanifold (11 to 15) of sleeves 7 and 8, thus forming an air film withinthe spaces 27 provided between the outer surfaces of sleeves 5 and 6 andthe inner surfaces of sleeves 7 and 8.

Since the air supplied by the conduits 26 is under pressure and theannular spaces 24 as well as the free spaces 23 enclosed by the shellpart flanges 21, 22, are tightly closed by these flanges, which bearagainst the sleeves 7 and 8 and the sidewall of the housing of theturbine rotor, the air supplied by conduits 26 produces an inflation ofshells 20 which accordingly operate in the same manner as tubelesstires.

In contradistinction to the gaskets of the known turbines which have acircular cross section, the shell parts 20 have the advantage that theyare not subjected to a pressing, but to a bending strain. Therefore,they can be made out of a material which is substantially harder. Testsmade with materials having a Shore hardness ranging above 90 gavesatisfactory results. The resiliency of the flanges of shell parts 20permits the turbine rotor to be freely floating within head 1, when theturbine is at rest, i.e. when the sleeve-supporting shells are notinflated.

Since the shell parts 20 are made out of a relatively hard material,they can easily be manufactured with precise sizes.

The material of parts 20 can, furthermore, be chosen so that these partsmay withstand temperatures ranging up to 260 C. so that the turbine canbe sterilized in the usual manner like all the other surgicalinstruments. VlTON (registered trademark) gives satisfactory results.

Since the suspension of sleeves 7 and 8 within head 1 is not ensured bythe compressibility of parts 20, butby the degree of inflation of theshells, the manufacturing tolerances of sleeves 7 and 8 as well as ofthe housing provided in head 1 and cover member 19 need not be as narrowas with the known turbines provided with gaskets having a circular crosssection.

Finally, the stiffness of the suspension of sleeves 7 and 8 can bemodified merely by varying the pressure of the air supplied to theturbine bearings. The dentist thus can modify the stiffness of thesuspension of his tool in accordance with the work he intends to carryout therewith.

I claim:

1. In a hand-piece of dentistry, an air-driven turbine comprising, incombination, a housing formed in the hand-piece and including asubstantially cylindrical sidewall, a main con duit provided in thehand-piece and extending across said sidewall for supplying the turbinewith air under pressure, a rotor adapted for carrying a tool and mountedin said housing within said sidewall for rotating coaxially therein athigh speed under the control of the jet of air under pressure suppliedby said main conduit, a pair of bearing sleeves located in said housingwithin said sidewall thereof for joumaling said rotor, inflatableplastic shells having openings therein inserted between said bearingsleeves and said sidewall for holding said sleeves radially within saidsidewall, each of said plastic shells comprising a pair of annularconcave radially supporting parts associated with each of said bearingsleeves and spaced apart axially with said openings in opposingrelationship, and a derivative conduit located in the hand-piececonnecting said main conduit to the opposing openings of said pair ofshell parts, the stiffness of the suspension of said sleeves beingmodified by varying the pressure of the air supplied through saidderivative conduit between said concave radially supporting shell parts.

2. In the hand-piece of claim 1, the rotor of the air-driven turbinebeing journaled by means of air bearings, each one of said bearingsleeves including a manifold having an inlet opening provided in theouter surface of the bearing sleeve and outlet openings provided in theinner surface of the sleeve for generating, between the bearing sleeveinner surface and the rotor outer surface surrounded by the bearingsleeve, the air film constituting one of the air bearings of said rotor,said plastic shell parts being located in either side of the inletopening of said manifold, an annular space being thus tightly enclosedby said shell parts, said bearing sleeve and the cylindrical side ofsaid housing, the openings of said plastic shell parts facing saidannular space and derivative conduit connecting said main conduit tosaid annular space.

3. In the hand-piece of claim 2, each part of said inflated plasticshells having a V-shaped cross section and being disposed so as to haveone leg of the V-shaped cross section in contact with said bearingsleeve and the other leg in contact with said cylindrical sidewall ofthe housing, the two parts associated with one bearing sleeve being,moreover, oriented in such a manner that the openings between the twolegs of each part are facing each other.

1. In a hand-piece of dentistry, an air-driven turbine comprising, incombination, a housing formed in the hand-piece and including asubstantially cylindrical sidewall, a main conduit provided in thehand-piece and extending across said sidewall for supplying the turbinewith air under pressure, a rotor adapted for carrying a tool and mountedin said housing within said sidewall for rotating coaxially therein athigh speed under the control of the jet of air under pressure suppliedby said main conduit, a pair of bearing sleeves located in said housingwithin said sidewall thereof for journaling said rotor, inflatableplastic shells having openings therein inserted between said bearingsleeves and said sidewall for holding said sleeves radially within saidsidewall, each of said plastic shells comprising a pair of annularconcave radially supporting parts associated with each of said bearingsleeves and spaced apart axially with said openings in opposingrelationship, and a derivative conduit located in the hand-piececonnecting said main conduit to the opposing openings of said pair ofshell parts, the stiffness of the suspension of said sleeves beingmodified by varying the pressure of the air supplied through saidderivative conduit between said concave radially supporting shell parts.2. In the hand-piece of Claim 1, the rotor of the air-driven turbinebeing journaled by means of air bearings, each one of said bearingsleeves including a manifold having an inlet opening provided in theouter surface of the bearing sleeve and outlet openings provided in theinner surface of the sleeve for generating, between the bearing sleeveinner surface and the rotor outer surface surrounded by the bearingsleeve, the air film constituting one of the air bearings of said rotor,said plastic shell parts being located in either side of the inletopening of said manifold, an annular space being thus tightly enclosedby said shell parts, said bearing sleeve and the cylindrical side ofsaid housing, the openings of said plastic shell parts facing saidannular space and derivative conduit connecting said main conduit tosaid annular space.
 3. In the hand-piece of claim 2, each part of saidinflated plastic shells having a V-shaped cross section and beingdisposed so as to have one leg of the V-shaped cross section in contactwith said bearing sleeve and the other leg in contact with saidcylindrical sidewall of the housing, the two parts associated with onebearing sleeve being, moreover, oriented in such a manner that theopenings between the two legs of each part are facing each other.